1,721,306 research outputs found
On the analysis of Sloshing of Water in Rectangular Containers: Numerical and Experimental Investigation
No full textA box-model approach for reservoir operation during extreme rainfall events: A case study
No full textExtreme rainfall events in an urban area pose various challenges to the water resource managers in terms of flood mitigation, inundation, water conservation and harvesting for drinking water supply. The objective of this study is to apply the box-model approach to evaluate reservoir operation during extreme rainfall events. A large water supply reservoir in Chennai was chosen to carry out this study. A box model, based on input–output parameters, is proposed to simulate the reservoir operation and hydraulic behaviour. Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS) has been used to simulate the reservoir inflow hydrograph and to understand the run-off characteristics of the basin. Three extreme rainfall events occurred in past have been selected for the analysis. Three different scenarios have been framed to assess the reservoir performance. Reducing the initial storage to 50% and releasing water at the beginning of the event gives a possible solution for flood mitigation in reducing the outflow volume by 9–37% and delaying the time to peak by 1–6 h. Though the reduced outflow volume from this reservoir is less, it can help to mitigate the flood inundation to a significant extent. Thus the box-model approach presented here can be utilised as a simple tool to generate the various combinations of outflow hydrographs for any reservoir
Bed shear stress in an evolving local scour due to a submerged turbulent jet flow
No full textA scouring experiment was performed and both the temporal evolution of the scour hole and the mean velocity field were measured. A mathematical model simulating the space-time evolution of bed shear stress inside a local scour, due to a submerged turbulent jet is developed. This model, using the scour hole’s temporal evolution as an input, is based on a modified Exner equation accounting for the scour hole’s steepness and then the critical bed shear stress, the bed load formulation and the structure of Exner equation are modified. The measured velocity field shows that the observed submerged jet flow, due to the interaction with the erodible bed changes into an asymmetric free jet flow. The spatial distribution of the hydrodynamic bed shear stress at different scouring stages was calculated for the performed laboratory experiment, and compared with the difference between the critical bed shear stress, accounting for the sloping bed, and the stress due to gravity, showing a gap decreasing as time increases
A mesoscopic model approach for polar fluid flow
No full textIn this paper we propose a mesoscale model for polar fluids and numerically investigate its validity by considering well known benchmark cases: the steady and unsteady Poiseuille and the low Reynolds lid-driven cavity flow. Analytical and numerical results are compared with our numerical results and a very good agreement is found. Then we consider not yet investigated high Reynolds lid-driven cavity flow cases, obtaining consistent and interesting results, which encourage to apply the proposed model to more complex cases
Discrete Boltzmann Numerical Simulation of Simplified Urban Flooding Configurations Caused by Dam Break
No full textThe Discrete Boltzmann Equation (DBE) is a versatile simulation method, consisting of linear advection equations, which can be applied to the Shallow Water Equations (SWE). The aim of this study is to assess the accuracy of the DBE to simulate dam-break of shallow water flows in presence of obstacles. Dam-break flows in the presence of obstacles can be regarded as simplified models for floods in urban areas. In this study, three cases of dam-break flows in the presence of obstacles are considered: two with an isolated obstacle and the third in presence of an idealized city. A comparison between DBE and benchmark results shows a fair agreement, confirming the validity of the DBE as simulation method for the SWE
On the Roll Motion of a Ship with Partially Filled Unbaffled and Baffled Tanks: Part 1: Mathematical Model and Experimental Setup – Part 2: Numerical and Experimental Analysis
No full textOn the Roll Motion of a Ship with Partially Filled Unbaffled and Baffled Tanks: Part 1: Mathematical Modelling and Experimental Setup
No full textClustering nonlinear time series with neural network bootstrap forecast distributions
No full textA new method for clustering nonlinear time series data is proposed. It is based on the forecast distributions, which are estimated by using a feed-forward neural network and the pair bootstrap. The procedure is shown to deliver consistent results for pure autoregressive dependent structures. It is model-free within a general class of nonlinear autoregression processes, and it avoids the specification of a finite dimensional model for the data generating process. The results of a Monte Carlo study are reported in order to investigate the finite sample performances of the proposed time series clustering approach. An application to a real dataset of economic time series is also discussed
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